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March 20, 1951 DE WlTT H. WYATT 2,545,680

SOLID-FUEL-BURNING SPACE HEATER WITH MAGAZINE AUTOMATIC DAMPERS AND HOT AIR JACKET Filed Nov. 14, 1945 6 Sheets-Sheet 1 Fi -l. .9

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SOLID-FUEL-BURNING SPACE HEATER WITH MAGAZINE AUTOMATIC DAMPERS AND HOT AIR JACKET Filed Nov. 14, 1945 6 Sheets-Sheet 2 I SHAME/MM De m2? Watt March 20, 1951 DE WlTT H. WYATT 2,545,580

SOLID-FUEL-BURNING SPACE HEATER WITH MAGAZINE AUTOMATIC DAMPERS AND HOT AIR JACKET 6 Sheets-Sheet 3 Filed Nov. 14. 1945 March 20, 1951 AUTOMATIC DAMPERS AND HOT AIR JACKET Filed NOV. 14, 1945 SOLID-FUEL-BURNING SPACE HEATER WITH MAGAZINE 6 Sheets-Sheet 4 DE WlTT H. WYATT- 545,680

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March 20, 1951 DE WlTT H. WYATT 2,545,680

SOLID-FUEL-BURNING SPACE HEATER WITH MAGAZINE AUTOMATIC .DAMPERS AND HOT AIR JACKET Filed Nov. 14, 1945 6 Sheets-Sheet 5 March 20, 1951 DE WITT H. WYATT SOLID-FUEL-BURNING SPACE HEATER WITH MAGAZINE AUTOMATIC DAMPERS AND HOT AIR JACKET Filed Nov. 14, 1945 6 Sheets-Sheet 6 .zewaz .HT Wyatt Patented Mar. 20, 1951 OFFICE SOLID-FUEL-BURNING SPACE HEATER WITH MAGAZINE AUTOMATIC DAMP- ERS AND HOT-AIR JACKET De Witt H. Wyatt, Columbus, Ohio Application November 14, 1945, Serial No. 628,443

6 Claims. 1

invention relates to space heaters and,

more particularly, to heaters or stoves of the .solid fuel-burningtype, having especial reference to room heaters employing vertical magazines in which coal, or other solid fuel, is introduced and. fed gravitationally to combustion grates.

- It is an object of the invention to provide a coal-burning space heater with improved means for. supplying combustion air under regulable flow to the grate structure and fuel combustion v zone of the heater, whereby to vary automatically and control the rate of fuel combustion in accordance with change in weather conditions or the heat requirements in the room or rooms heated by the heater.

Another object of the invention is to provide a space heater in which the hot gases of combustion, following their generation and release from the burning fuel, are caused to flow in intimate contact and heat-exchanging. relationship with 'the heat-conducting walls of a multiplicity of vertically extending channels provided in a' heattransferring radiator arranged within the outer casing of the heater, room air bein introduced into the bottom of the casing and confined'for flow over the outer surfaces of the radiator, whereby to heat the room air prior to its release through outlets provided therefor in the top of the heater casing.

. A furtherobject is to provide a heater of this character with a thermostatically regulated bypass valve which, when opened, diverts'the hot flue gases from their normal travel through the radiator channels and allows such gases to pass, in full or in part, directly into the associated outlet fiue of the heater, whereby to promote initial combustion of the fuel and effect rapid heating of the outlet flue and its associated chimney, so that normal circulation of the flue gases under changing draft conditions may be quickly and readily established.

Still, a further object is to provide such a heater with a plurality of room air-admitting passages having swinging and balanced dampers responsive to flue or chimney drafts, the said dampers opening or closing automaticall as the draft increases or decreases, whereby to provide for increased or diminished air flowthrough said passages and automatically controlling the rate of fuel combustion and the maintenance of uniform temperatures and room areas under the influence of the heater.

In connection with the foregoing objects, I have worked out a number of novel structural details and part arrangements which will be more thortherethrough drawn from the ash pit 2!.

positioned a grate ring 19.

2 oughly understood by reference to the following description and the accompanying drawings, wherein:

Fig. 1 is a vertical sectional view taken through a coal-burning space heater formed in accordance with the present invention;

Fig. 2 is a similar view on a plane perpendicular to that of Fig. 1, as indicated by the line 2-2 of Fig. 1; I

Fig. 3'is a horizontal sectional view on the line 33 of Fig.1; v

Fig. 4 is a similar view on the line 44 of Fig. 1;

Fig. 51s a detail sectional view disclosing the by-pass valve and its associated thermostatic controls; q

Fig.6 is a rear elevational view of the mechanism disclosedin Fig. 5;

Fig. 7 is a detail-vertical sectional view taken through the thermostatic control forthe by-pass valve on the line 1-1 of Fig. 5;

Fig. 8 is a vertical sectional view through the thermostatic bellows having a user's adjustment;

Fig. 9 is a perspective View disclosing the exterior appearance of my improved space heater.

Referrin 'more particularly to the drawings, my improved heater comprises a casing structure, indicated in its entirety by the numeral H], of any suitable external configuration, such as the substantially cubical design disclosed in Fig. 9; The casing structure includes a base ll having mounted thereon guides I2 for the slidable support of an ash receptacle |3.' Also formed with the base is an air-admitting grille I 4, by which air drawn from the floor is admitted into the casing structure for heating purposes' The front of the base is formed with an openi-ng'for the slidable reception of the receptacle I3. At the rear of the casing structure, the base is formed with a water-receiving chamber 15, accessible by a hinged lid I6, said chamber being adapted to receive a body of water which, under the operation of the heater, is vaporized to control the humidity of the warmed air.

Supported on the base is an inner casing or radiator 11, the latter being formed at its bot tom with a horizontal flange l8. upon which is Rotatable on the ring I9 is a metallic or ceramic grate member 20. This member is substantially hollow and has its walls formed with openings for the passage'of air The grate member, in this instance, is formed with a spider 22 having projecting ends which receive rollers 23 by which the grate member is rotatably supported on the ring 19. Riotatably supported in the ash pit is a shaft 24 having an exteriorly is provided with a vertical series of louver openings 21, by which room air may be admitted into the air-heating passages 28 :formed :between the walls of the inner and outer rcasings. Adjacent to the openings 27, the front wall of the inner casing is formed with an opening .25, which is normally closed b a pivotally movable weightbalanced damper 36. When the heater is "inactive operation, and responding to chimney draft, the damper 30 swings inwardly, providing for air flow through the passage 3| of the inner casing into the ash pit 2i and thence through the grate member.

It will be understood that the openings in the grille l4 admit air into the passages 2-8 provided between the inner and outercasingu-nits, but do not freely admit air into the ash pit, except through the operation of the barometric damper 3B. Disposed centrally within the casing structure above the grate ring I9 is a refractory'iire bowl 32, solid fuel'being admitted into this bowl by way of the removable lid 33 fer-med in the central top portion of the outer casing 26. The bowl forms the lower part of a fuel magazine which possesses fuel storage capacity, so that the heater may operate for sustained periods of time without fuel replenishment. As the coal descends gravitationally through the fuel magazine toward the grate member, its temperature is progressively increased until active flame-producing combustion is present. The refractory elements 32 from which the fire bowl is formed are provided at intervals with slots 34 by which a secondary supply of air is admitted into the fuel contained within the fire bowl to effect active combustion thereof and minimize smoke formation, and also, to supply sufficient air to sustain combustion when the passages through the grate member are obstructed by ash accumulations.

Exteriorly, the fire bowl is surrounded by an air-confining casing 35 which communicates with a passage 36, formed in the inner casing l'l adiacent to the passage 3| (see Fig. 1). To admit room air into the passage 36, the front wall of the inner casing is formed with an opening 3? arranged in registration with the louver openings 27. A pivotally mounted weighted damper 38 normally closes the opening 31', but when the heater is in operation, the damper 38 swings to an open position providing for the flow of air through the passages 36 and into the casing 35 and thence through the slots 34 of the fire bowl to promote fuel combustion within the latter.

Above the fire bowl 32, the Walls of the inner casing I'l effect the support of a head ring or shield 39 preferably formed from a ceramic or other refractory material. The opening in the center of the ring 39 receives the lower end of a magazine throat 40, which depends from the.

ring 39 and forms an air chamber 45. This chamber is in communication with a vertical passage 46 formed by the walls of the inner casing. Air from the louver openings 21 or the air heating space 28 is drawn into the passage 46 through an opening 41 which is controlled by a pivoted and weight-balanced damper 48. Thus, when the heater is in operation, and respondingto chimney draft, the damper 48 opens to admit air into the passage 46 and thence into the chamber 45, the air passing from said chamber through a plurality ofslots-Mformed in the head ring 39. This tertiary supply of air is commingled with the volatiles or smoke released from the distilling fuel, producing combustion thereof and minimizing smoke formation. It will be understood that the dampers 60,38 and 48 are provided with adjustable weights 50 so that their response to given draft conditions may be readily regulated.

The gaseous products of combustion pass outwardly "through the open top of the fire bowl 32 and, under normal conditions, flow downwardly, as indicated by the arrows A :in Fig. 2, through passages 5| 'formed'between the bowl and its surrounding casing 35 and the inner circular walls 52 of the inner casing. At its lower end, the passage '5l is in open communication with the lower ends of a plurality of line passages or channels 53 formed by'the corrugated walls 54 of the inner casing elements. (See Figs. 2 and 3. The rice gases pass upwardly through the passages 53-, as indicated by the arrows B, and enter an ouflet chamber '55 formed in'the top of the casing structure and which communicates with a flue outlet 56 leading to an outlet stack or chimney. "The hot gases during their travel through the passages 53 heat the corrugated walls 54 so that the latter, in turn, may be-employed in heating the room air flowing through the passages 28.

It will be understoodthat the room air is drawn into the heater through the openings in the grille l4 and through thermal circulation moves upwardly into contact with the outer surfaces of the corrugated walls 54 and, following such heating, escapes through openings 51 provided inthe top of the outer casing. By corrugatin'g th wall 54, its surface area is increased whereby to provide improved heat transfer between the heated gaseous products of combustion and the room air undergoing heating thereby.

In certain stages of operation of the heater, as when combustion is being initiated therein and chimney drafts are negligible, it is desirable to by-pass the passages 53 so that the gaseous products of fuel combustion may flow directly from the bowl to the fiue gas outlet. To accomplish this, the inner casing is provided with a by-pass opening 58 in registration with thetop of the fire bowl. This opening is normally closed by an automatically actuated damper or by-pass valve 59. The latter opens or closes the opening 58 with a quickly executed snap action, and such opening or closing is automatically accomplished in accordance with the temperature of the flue gases passing from the heater to the chimney. The valve or damper 59 is carried by the outer end of the longer arm of the bell crank lever 68, which is pivotally mounted as at 6! on a stationary support. The shorter arm of the bell crank lever is pivotally connected as at 62 with an arm 63, the latter being supported interm'ediately of its length by a pivoted link element 64. The outer end of the arm 63 is movably associated with the damper-actuating stem 65 of an adjustable up er portion of the housin 61.

thermostatic unit 55 adaptable for user adjust- This unit c niprises as shown Fig 8. a housing 61, which is seated on an upper wall .63 of the heater easin contiguous to the flue gas outlet thereof, thehousing being accessible exteriorly of the heating casing. Disposed within the ca ing and positioned on the upper surface of the wall 58 are gaskets 5.9 and a bottom plate 19,, gaskets and plate being disposed over an ope ing 1-! formed in the wall 68. said plate and gaskets are formed with axial openings 12 for the slidable reception or a thermostatic well element 13. This element is formed with heat absorbing 14 which are arranged in the path of hue gases immedi tely prior to the dis h rg of the same from the heater,

The element 13 includes an axially disposed cavity 15 for the reception of a low boiling point liqu d. Above the plate 10', he element 13 tor mine-tee in n enlarg d h ad 16 with which is connected the lower nd of a bell ws 11. The upper end or the bellows is conn cted with a ticellv adjustable disk. :8, the latter having its periphery slott d as at it, to receive the shanks of s rews 80., the latter protecting upwardly from the head 15 and having their threaded ends re ceived witiun openings formed in the housing 51, The disk is formed with an upwardly projecting threaded stud 8 which is receivable within an internally threaded bore 82 providedin a th mble 8'3, which is rotatably journaled in the Connected as at 84 with the thimble B3 is a thermostateadlustin knob 85, The lower ed e of this knob s formed with an indexing po nter at, which is m able with r spect to indicia-b aring strip stationarilv inser ed in the exterior wall of the housing 61. o

By turning he kn b 85. e her to heright or l ft, corresponding ver ical movement will be imparted to the disk 18, hereby verning he response of the bellows 11 to internal pressures created by the vaporization of the liquid cone tained within the cavity 15 of the, element 13. If the t mperature of the flue gases leaving the heater is too high for a given setti g of the kno 85, the internal gas pressure within the bellows will cause the head 15 to assume its extreme downward position, as shown in'Fig, 8.- Such downward movement or the element 13 produces ac mp nyin 'movernent of the associated stem .As shown more particularly in Figs. and 7, the, lower end or the stem 65 is threadedas at 90 and positioned in an opening formed in the top of a bail 9L Lock nuts 92 are received on the threads of the stem to main ain the bail in desired position f adjustm nt, The bail is formed with a pair of cross webs 93 which carry vertically aligned adjustable set screws 94 between which the outer end of the lever 63 is positioned.

The extreme lower end of the stem 65 is p vided With an adjustable conically pointed bearing element 95 which is received in a depression 96 provided'in the horizontal arm 91 of a sub= stantially T.-shapedlever $3, the latter being fulcrumed for movement about a horizontal pin 99 carried by a removablepanel- H30.

Above the pivot pin 99, the vertical arm of the lever 98 is formed with a depression H for the reception of the pointed end of a movable bellows stem I02, the latter being actuated by a thermostatic room ternperature bellows I83.

which is mounted in a casin in detaohably connected as at M5 to the back wall of the heater The lower part of the vertical arm of the lever 98 is formed with a depr ssion 106, which receives the pointedv end of a spring-pressed stem 101. This stem is formed with a collar f r engagement with one end of a coil spring 108, the other end of said sprin ngaging with a seatin block J09, which is slidably adjustable in a socket [I0 formed in the casing W4. A set screw NI may be used for controlling the positions of the block 140.9 and the tension-exerting force of the spring Hi8, thus balancing the action of the .bellows 11 of the users thermostatic control as desired r a The link 64.15 formed with a depression H2 with. which engages the pointed inner end of a stem H3, the latter protecting rigidly from one side of a frame H4 which surrounds the bail 9|. The opposite side of the frame H4 is formed with a squared shank l which i slidablv received in a correspondingly formed opening provided in the panel I00, and is formed with a collar which acts as a seat for one end of a coil pring I I6. The Opposite end of this spring one gages with an adjustable seating block H1, which i slidablein a socket 118 formed in the casing :04 below the block 409. An externally accessible set screw H8 is carried by the casing I04 for controlling the adjustment of the block H1 and the tension of the associated spring H6,

The lower end of the bail 9! is disposed adjacent to and immediately over the free end of an arm I20 which is carried by a check damper I21, the latter being pivoted as at I22 and adjustably weighted as at I23 so that normally the damper l2! arrests air flow through an opening I24 formed at one end of the air conducting pas sage I25 leading from the ash pit 2!. When the bail 9! descendsunder the action of the adjustable users control 66 and the room temperature thermostat )3, the check damper I2! is opened to admit of air flow directly from the ash pit, or below the grate 20, into the waste gas outlet of the heater. The room temperature bellows I03 is connected by means of a capillary tube I26 and the bulb I21 adapted for the reception of a readily volatilizable liquid. The bulb 121 is preferably'in the form of a coil to provide reater heat transfer surface! The balance spring I08 is set to exert a pressure against the T-shaped lever 98 in an upward direction and against the force of the thermostatic bellows of the user con rol 66 and the room control I 03. This arrangement balances stack temperature against room temperature, with the spring balance located in the back of the heater in a relatively low and cool location. The user control 55 has a limited range of adjustment from approximately 40 to 80 F. and has no springs or exposed moving parts to develop obvious troubles from soot or heat. The adjustment balance is set to permit the push rod to move downwardly suflicie'ntly in response to the warming up of the flue box 55 to close the snap action by-pass valve 59, the damper It! being op ned by additional downward movem n of t push rod, this action being au mented by p essure developed in the room temperature bellows W3, as returning room air; passing over the bulb I21 at the base of the stove increases in temperature. Increased temperature of the returned room air builds up a gas pressure the hermetically sealed 7 liquid-filled bulb I21, and this is transmitted by the capillary tube I26 to the bellows I03. I

As the room warms up and the stack temperature of the out-going gases is sufficiently warmed to insure safety, that is, sustained stove operation, the pressure in the thermostatic bellows I03 builds up and reduces the resistance on the push rod 65 as exerted by the spring I08, permitting the flue box bellows to open the check damper IZI sufficiently to divert air in part from the grate and the ash pit 2| and allow it to pass directly into the flue box 55 through the opening I24. When the check valve I2I is held open by the push rod, the balance damper 30 takes over and feeds air through the ash pit 2| directly into the flue box. The valve 33 then acts as a barometrically controlled, back draft, check damper. This checking arrangement keeps objectionable gases from collecting in the ash pit, keeps the latter at a low temperature, removes cold air from lower floor levels and provides a quick correction of combustion conditions.

Basically, the controls provide a combination of operational regulation from three sources: First, draft pull; second, stack temperature; and, third, room temperature.

It willthus be seen that the present invention provides an improved heater for the burning of solid fuels. The magazine of the heater is formed so that it possesses fuel storage capacity, where by to enable the heater to operate for prolonged periods of time without fuel replenishment. As the fuel descends toward the active zone of combustion, its temperature is progressively increased to liberate therefrom gases and volatiles which are efficiently consumed, so that little or no smoke is produced, particularly after combustion has been initiated.

In the initial combustion stages, the by-pass valve 59 is open so that any smoke which is generated at this period passes readily into the stack outlet or chimney, without gaining access to the atmosphere of the room in which the heater is positioned. After desired combustion has been initiated, the by-pass valve 59 is closed by the automatic actuation of the bellows of the thermostat unit 66. This enables the major part of the primary air entering the heater through the ash pit to pass directly through the grate structure into the burning fuel. The heater is designed to function efiiciently on virtually all commercial grades of bituminous coal employed for house heating purposes and does not require the use of special fuels of selected sizes. In introducing combustion air into the heater or stove, I utilize a combination of barometric dampers, indicated at 3%, 38 and 48, operating on full draft pull or suction. These dampers cooperate with the thermostatically-actuated bypass valve 59 to vary the calibration of the automatic balance control of said dampers, thereby increasing or decreasing the quantity and location of combustion air entering the fuel combustion zone. By the use of barometric dampers, the power required for their operation is very slight, as this type of damper is set on balance to operate normally on the suction of the draft. It will be noted that there are three levels of automatic supply for combustion air. Thus, when ashes are produced to an extent that they cover the primary air supply through the bottom grate, the draft burner will provide air through the center damper 3B, which is separated from the lower damper 30 by a barrier wall.

Then, if additional air is needed, the draft burner opens the top draft or damper 48, thus assuring an adequate supply of air tosustain properly fuel combustion.

The draft pull mentioned above is controlled largely by the thermostatic unit 66, with its separate assembly on the back of the heater. Most of the controls are factory established, and the only control necessary for the user of the stove to operate is the knob on the thermostatic unit. When the by-pass valve 59 is closed, the check damper I2I is used to regulate the heater operation. By the provision of the check valve or damper I2 I, air is taken from under the grate and by-passed to the waste gas outlet of the heater, thereby decreasing the volume ofprimary air supplied to the fuel and lowering the rate of fuel combustion.

My improved heater, as constructed, permits the use of high temperatures and smokeless and efl'icient combustion. In the high temperature regions, the burning fuel contacts with refrac tories capable of withstanding high tempera tures. Beyond the high temperature zone, use is made of metals which are light in weight, provide for eflicient heat transfer and which are not detrimentally affected by the'h'eated' gases contacting therewith, the entire structure being designed for compactness, lightness in weight and heating efficiency.

Iclaim:

l. A solid fuel-burning heater comprising: a casingstructure having a base, outer vertical side walls and a vented top,'said base including an ash pit having an air inlet, a grade at the top of said ash pit, a fire bowl arranged above and in registry with said grate, said bowl being open at its top and bottom and formed with orificed side walls, fuel inlet means passing through the top of said casing structure and disposed centrally of the latter for conducting fuel gravitationally to said bowl and grate, a horizontally extending refractory shield member arranged in' said casing structure above and in spaced relation to said flre bowl and surrounding the lower end of said fuel inlet means, an inner vertical wall depending marginally from said shield member, said inner wall being positioned around said bowl in spaced relation therefrom to provide a chamber below said shield member and above said fire bowl, said chamber communicating with a passage formed around said bowl by said inner vertical wall for the downward flow of gaseous products of combustion released from the top of said bowl and delivered to said chamber and the upper part of said passage, an intermediate wall positioned between the outer vertical walls of said casing structure and said inner wall, said intermediate wall being spaced from said inner Wall to provide a flue gas passage, means connecting said flue gas passage with said inner wall passage at the bottom of the latter, said flue gas passage being disposed for the upward flow of said products, means forming a gas chamber in the upper part of said casingstructure by said inner and intermediate walls communi-' eating with said flue gas passage there being a flue gas outlet leading from said flue gas chamber, said flue gas outlet being formed in one of the walls of said casing structure contiguous to the top thereof, said intermediate wall being spaced from the outer walls of said casing structure to form an air-heating passage open at the bottom thereof to the atmosphere and leading through said casing structure from the base to' A solid fuel-burning heater as defined in claim 1, and wherein said casing structure is formed internally with a divisional'wall defining an air-conducting passage leading from the ash :pit to the flue gas chamber independently of the inner and intermediate wall passages, and a damper valve positioned in said divisional wall, said damper valve functioning when open to admit of the fiow of air from said ash pit into said flue gas chamber and diverting in part the flow of combustion air to said grate structure and fire bowl.

" 3; A heater for burning solid fuels, comprising a casing structure provided with an ash pit in the bottom thereof formed with an air inlet,

a fire bowl open at its top and bottom and formed with air-admitting orifices inits side walls, a perforate grate arranged in the bottom of said vfire bowl and providing for air flow from said ash pit into the bottomof the fire bowl, rela- 'tively spaced substantially vertically disposed inner, intermediate and outer walls forming elements of said casing structure, an air-conducting shell surrounding said fire bowl, and means including said inner wallforming an air inlet a passage communicating with an opening in said intermediate wall and with said shell, a barometric valve normally closing said opening,a shield member supported by said inner-wall above the open top of said fire bowl, to provide a chamber formed tbetween the top of said fire bowl and said shield member within the confines of said inner wall for the reception and passage of gaseous products of combustion released from the top of said fire bowl, said chamber being in open communication with an initial downwardly extending fuel gas passage for such products, said initial passage being disposed between said shell and said inner wall, the spacing of said inner and intermediate walls being such as to provide a second fuel gas passage and means connecting said second passage with the bottom of said initial downwardly extending passage, said second passage being adapted for the upward flow of said products from the bottom of said initial passage and means forming a flue gas chamber formed in the upper part of said casing structure between said inner and intermediate walls and communicating with said second pasage, said last-named chamber being in communication with a flue gas outlet provided in the outer walls of said casing structure, said intermediate and outer walls being relatively spaced to form an air-heating passage open at its lower end to the atmosphere and leading from the lower part of the casing structure to the top part thereof and adapted for the passage of atmospheric air in heat-exchanging relationship with the surfacess of said intermediate wall.

4. A heater utilizing solid fuels, comprising a casing structure including a base, outer vertical side walls and a vented top, said base being formed to provide an ash pit formed with an air inlet, a grate mounted in said casing structure above said ash pit for the passage of combustion air drawn into said ash pit in an upward direction through the grate, a' firev bowl arranged above and in registry with said grate for thereception of solid fuel, fuel-admitting means by which solid fuel is admitted into said fire bowl from the vented top of the casing structure, said bowl being open at its top and bottom and formed with air-admitting ports in the side walls thereof, substantially vertically disposed and relatively spaced inner and intermediate walls forming a part of said casing structure and disposed within the vertical side walls of the casing structure above said base, an air-supplying shell surrounding'said fire-bowl, means including said inner wall formed to provide an air-transmitting passage which communicates atone end with the interior of said shell and at its other end with an opening formed in said intermediate 'Ywall, there being an air-transmitting and heating passage formed between said intermediate wall and the vertical side walls of said casing structure, said last-named passage being in open communication with the atmosphere at the base of said casing structure and'with the vented top thereof, a pivoted barometric damper governing the inflow of air through the opening provided in said intermediate wall for causing air flow through the passage leading to said shell, said inner and intermediate Walls below said damper being formed to define another air passage leading from the air-conducting and heating space between the intermediate wall and one of said f outer walls to said ash pit, a second barometric valve governing inflow of air from said air space j between the intermediate and outer walls for 'ftransmission to said ash pit, a shield member j supported by said inner wall above the top' of said fire bowl and providing therebetween a m chamber forJthe reception and passage of gaseous products of combustion released from the top of said fire bowl, the spacing of said inner and intermediate walls being such as to provide elongated passages for the transmission of said gaseous products of fuel combustion, said passages communicating openly with said shield member chamber a flue gas chamber means formed in the top of said casing structure between said inner and intermediate walls, said last-named passages communicating with said flue gas chamber means, and a bypass valve normally closing a bypass opening provided in said inner wall to establish direct gas flow communication between said shield member chamber and the fiue gas chamber.

5. A heater utilizing solid fuels as defined in claim 4, and wherein means including said inner, intermediate and outer walls of the casing structure form a confined air-conducting passage which leads from said ash pit through a closeable opening to said flue gas chamber, whereby to conduct air directly from the ash pit of the casing structure to said flue gas chamber, and movable valve means normally arresting air fiow through said closeable opening.

6. A solid fuel-burning heater comprising: a casing structure having a base, outer vertical side walls and a vented top, said base including an ash pit having an air inlet, a grate at the top of said ash pit, a fire bowl arranged above and in registry with said grate, said bowl being open at its top and bottom and formed with orificed side walls, fuel inlet means passing through the top of said casing structure and disposed centrally of the latter for conducting fuel gravitationally to said bowl and grate, a horizontally extending -11 .i iefmctor hi drm m r n d in S i 2 n s ruct re ab ve. a d in pa re a Said fire .bovvl and surrounding the lower end of said f.u inletme n nne v ti wel de n in ma al rqma a dr S i d me e ai inner wall being positionedv around said bowl in vspacedrelation.therefrom to provide a chamber .helow said shield melp ber and above said fire .boyvl, said chamber communicating with a passage formed around vsaid bowl by said inner verticaiwall for the downward flow of gaseous prod- V..uc ts of combustion released from the top of said loovvl and delivered to said chamber and the zu erna t fsaid passage, a e m w Wall positioned betyqeenthe outer vertical walls of a,id 2.$ i1'lg structare and said inner wall, said intermediate wall being spaced from said inner ,vg ali t provide a flue gas passage, means connecting said flue gas passage withsaid'inner Wail gassageat the botto m of thelatter said flue "gas :pa'ssage being disp os'edfontlie up'vvard new of said, p roducts, means .forming a gas chamber in the upper part gffsaid'casiiig structure by said i ner and 6 intermediate walls, 'cornmunicating :w ti said; flue gas passage there being a 'fiuegas ontlet leadiing iron said'fiue gasc h'amber, said .fiu gese lile be ng ,fq fil inf f the W l flotsam eas n si iieim'w t u to the "t thereofijs 'd intermediate vvall being spaced from t het outer walis lof 's'aidcasi rig structure to form 30 anfair' heating baisae open' at the bottom there- I of to' the atriiosp'herearid leading through said ica siri'gjstructureflfrorn tfie base to its vented top andadapted rar ng pa s ge ofatmo'spheric air in 25 Number ja fia as aaaea s eMa m a t n 9 em j ii esuirerel ame a iv ga 'chamber for automatica1iy' operatifig said bypass vf'e with the "tm sefa r -onerii'rr'g and closing bi-1tiia aaaoftfieaimla aver .7 a a.

' EWITT HJWYATT.

REFERENCES CITED The following references are ofTEbrdifithe T116 6f17hiS 'ia'aitent:

Name Date "345,564 "A'lsop 'July 13, 1886 1503,112 Morse -Apr.-2s,-1s93 1759.,313 Sayre May 10, 1904 FoRE'IGN-riiTENTs ber .rmqq r Pl e 38 896 Tfiermen 239N12 1. 9 ie afisfi D 111 3 imam y 1,. 3

' 797,494 France F'eb. I7, 1956 ng opening oijer'ation I 

